What is agglomerative clustering

Agglomerative clustering is a type of unsupervised machine learning clustering algorithm that groups data points into clusters based on their similarity. It is a bottom-up approach in which each data point is initially considered its own cluster. The algorithm then iteratively merges the most similar clusters to form larger clusters until all data points are in one cluster. This type of clustering is useful for exploratory data analysis and can be used to identify clusters of similar data points in a dataset.